Hi,
I'm not sure what their price range is, but one option is
Vacation rentals, private rooms, sublets by the night - Accommodations on Airbnb - a site where people post their homes/apartments/condos for rent either by the night, the week, month, etc. I took a quick glance at the places available in Raleigh and they seem to run between $800 and close to $2K per month.
Another option is Craigslist, of course. Though it may take a little bit more work on your part to make sure everything is legit, you can still find places and it's where a lot of people post sublet needed info, etc. Use your common sense and you'll be fine!
Good luck!